LTC1474/LTC1475
PIN FUNCTIONS
V
OUT
/V
FB
(Pin 1):
Feedback of Output Voltage. In the fixed
versions, an internal resistive divider divides the output
voltage down for comparison to the internal 1.23V refer-
ence. In the adjustable versions, this divider must be
implemented externally.
LBO (Pin 2):
Open Drain Output of the Low Battery
Comparator. This pin will sink current when Pin 3 is below
1.23V.
LBI/OFF (Pin 3):
Input to Low Battery Comparator. This
input is compared to the internal 1.23V reference. For the
LTC1475, a momentary ground on this pin puts regulator
in shutdown mode.
GND (Pin 4):
Ground Pin.
SW (Pin 5):
Drain of Internal PMOS Power Switch. Cath-
ode of Schottky diode must be closely connected to this
pin.
SENSE (Pin 6):
Current Sense Input for Monitoring Switch
Current and Source of Internal PMOS Power Switch.
Maximum switch current is programmed with a resistor
between SENSE and V
IN
pins.
V
IN
(Pin 7):
Main Supply Pin.
RUN/ON (Pin 8):
On LTC1474, voltage level on this pin
controls shutdown/run mode (ground = shutdown, open/
high = run). On LTC1475, a momentary ground on this pin
puts regulator in run mode. A 100k series resistor must be
used between Pin 8 and the switch or control voltage.
FUNCTIONAL DIAGRA
LBI/OFF
1µA
LTC1474: RUN 8
LTC1475: ON
4.75µs
1-SHOT
TRIGGER
OUT
SW
5
V
OUT
1×
20×
STRETCH WAKEUP
LBO
2
+
LB
–
READY
3
LTC1474: LBI
LTC1475: LBI/OFF
×
CONNECTION NOT PRESENT IN LTC1474 SERIES
CONNECTION PRESENT IN LTC1474 SERIES ONLY
W
U
U
U
U
U
100mV
V
IN
7
R
SENSE
(OPTIONAL)
V
CC
–
×
C
ON
+
V
IN
+
–
V
ON
6
SENSE
5Ω
+
+
1.23V
1.23V
REFERENCE
4
GND
1M
3M
(5V VERSION)
1.68M
(3.3V VERSION)
V
OUT
/V
FB
1
OUTPUT DIVIDER IS
IMPLEMENTED EXTERNALLY IN
ADJUSTABLE VERSIONS
1474/75 FD
5
LINER [ LINEAR TECHNOLOGY ]
